There are various occasions, such as when a camera is on a mobile robot, when it is important to ascertain from the view seen by the camera of the pose (i.e., the position and orientation) of the camera. Typically this is done by searching the view for known features, either shapes or points, as determined by edges and comers of known objects or for specially designed calibration objects known to be in the picture scene. If there is known the geometry of the features and if one can uniquely identify them in a perspective image taken by a camera whose intrinsic parameters are known, then pose estimation becomes a classical problem of photogrammetry and computer vision. Such problems are amenable to solution by known techniques. In these cases, however, pose estimation generally involves first determining the precise location (via sophisticated image analysis algorithms) of the features whose intrinsic geometry was assumed to be already known. This reduces the problem to the equivalent algebraic-like framework of feature points whose precise perspective projection is provided by the images seen.
However, such currently used methods are based on feature identification and require rather extensive image processing and analysis to locate with the required precision the geometric elements necessary for the algebraic computation of the desired spatial pose.
In spite of the fact that it was recognized early on that in many cases of practical importance one can actually produce and deploy in the environment being viewed calibration objects, such objects were generally designed with the aim of making it easier for the image analysis procedures to locate precisely various features. The present invention takes a new approach that should usually lead to the simplification of the image analysis procedures.